JP2003202836A - Device and method for driving display panel - Google Patents

Device and method for driving display panel

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Publication number
JP2003202836A
JP2003202836A JP2001401814A JP2001401814A JP2003202836A JP 2003202836 A JP2003202836 A JP 2003202836A JP 2001401814 A JP2001401814 A JP 2001401814A JP 2001401814 A JP2001401814 A JP 2001401814A JP 2003202836 A JP2003202836 A JP 2003202836A
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JP
Japan
Prior art keywords
current value
light
display panel
light emitting
driving
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2001401814A
Other languages
Japanese (ja)
Inventor
Shinichi Ishizuka
Hideo Ochi
Tsuyoshi Sakamoto
Masami Tsuchida
正美 土田
強 坂本
真一 石塚
英夫 越智
Original Assignee
Pioneer Electronic Corp
パイオニア株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pioneer Electronic Corp, パイオニア株式会社 filed Critical Pioneer Electronic Corp
Priority to JP2001401814A priority Critical patent/JP2003202836A/en
Priority claimed from US10/322,776 external-priority patent/US7274363B2/en
Publication of JP2003202836A publication Critical patent/JP2003202836A/en
Pending legal-status Critical Current

Links

Abstract

(57) [Summary] An object of the present invention is to provide a driving method and a driving device of a display panel capable of performing high-quality image display without luminance unevenness even when used for a long time. A light-emitting drive current value flowing when each light-emitting element for each pixel emits light independently is measured in association with each pixel, and is associated with a pixel corresponding to input pixel data. Based on the light emission drive current value, the luminance correction is performed on the input pixel data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device and a driving method for an active matrix type display panel.

[0002]

2. Description of the Related Art At present, an electroluminescence display device (hereinafter, referred to as an EL display device) equipped with a display panel using an organic electroluminescence device (hereinafter, simply referred to as an EL device) as a light-emitting device for carrying out a pixel is known. Attention has been paid. As a driving method of the display panel by the EL display device, a simple matrix driving type and an active matrix driving type are known.
The active matrix drive type EL display device has advantages such as lower power consumption and less crosstalk between pixels than a simple matrix type, and is particularly suitable for a large screen display and a high definition display. Are suitable.

FIG. 1 shows an active matrix drive type E.
It is a figure showing the schematic structure of L display device. As shown in FIG. 1, the EL display device includes a display panel 10.
And a driving device 100 for driving the display panel 10 according to a video signal. The display panel 10 includes:
Anode power supply line 16, cathode power supply line 17, 1 screen n
Scanning lines (scanning electrodes) A for each horizontal scanning line
1 to A n, and m data lines (data electrodes) B 1 .about.B m arranged in intersecting each scanning line are respectively formed. The drive voltage Vc is applied to the anode power supply line 16, and the ground potential GND is applied to the cathode power supply line 17. Furthermore, at each intersection of the scanning lines A 1 to A n and the data lines B 1 .about.B m in the display panel 10, EL unit E 1 serving as pixels, 1 through E n, m are formed.

FIG. 2 is a diagram showing an example of the internal configuration of an EL unit E formed at the intersection of one scanning line A and one data line B. In FIG. 2, a scanning line A is connected to a gate G of a scanning line selecting FET (Field Effect Transistor) 11, and a data line B is connected to a drain D thereof. The source S of the FET 11 is connected to the gate G of the FET 12 as a light emission driving transistor. A drive voltage Vc is applied to the source S of the FET 12 via the anode power supply line 16, and a capacitor 13 is connected between the gate G and the source S. Further, the drain D of the FET 12 has E
The anode end of the L element 15 is connected. EL element 1
A ground potential GND is applied to the cathode terminal of the transistor 5 via a cathode power supply line 17.

[0005] drive 100 sequentially to the scanning lines A 1 to A n each display panel 10, continue to apply an alternative scanning pulse. Further, the driving device 100 synchronizes with the application timing of the scanning pulse to generate pixel data pulses DP 1 to D corresponding to the input video signals corresponding to the respective horizontal scanning lines.
P m are generated and applied to the data lines B 1 -B m respectively. Each of the pixel data pulses DP has a pulse voltage corresponding to the luminance level indicated by the input video signal. At this time, the scanning line A to which the scanning pulse is applied
Each of the EL units connected above is a target of writing pixel data. The FET 11 in the EL unit E to which the pixel data is to be written is turned on in response to the scan pulse, and the pixel data pulse DP supplied via the data line B is transmitted to the gate G of the FET 12 and the capacitor 13. Each is applied. The FET 12 generates a light emission drive current according to the pulse voltage of the pixel data pulse DP, and supplies this to the EL element 15. In response to the light emission drive current, the EL element 15 causes the pixel data pulse D
Light is emitted at a luminance corresponding to the pulse voltage of P. During this time, the capacitor 13 is charged by the pulse voltage of the pixel data pulse DP. By such a charging operation, a voltage corresponding to the luminance level indicated by the input video signal is held in the capacitor 13, and so-called pixel data is written. Here, when the pixel data is released from the writing target of the pixel data, the FET 11 is turned off, and the supply of the pixel data pulse DP to the gate G of the FET 12 is stopped. However, even during this time, the voltage held in the capacitor 13 continues to be applied to the gate G of the FET 12 as described above.

Here, the EL element 15 has a characteristic that the resistance value of the element itself gradually increases when light is emitted for a long time. At this time, since the EL elements 15 in the EL units E 1,1 to En , m mounted on the display panel 10 have different light emission frequencies depending on the input video signal, the accumulated light emission time also differs. . Therefore, when the display panel 10 is driven for a long time, the resistance value of each of the EL elements 15 varies, and the resulting variation in the luminance causes a problem that luminance unevenness or burning occurs on the entire screen.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a problem, and a display panel capable of displaying a high quality image without luminance unevenness even when used for a long time. A driving device and a driving method are provided.

[0008]

A display panel driving apparatus according to the present invention is a display panel driving apparatus for driving a display panel in which a plurality of light emitting elements each carrying a pixel are arranged in a matrix. A drive voltage generating circuit that supplies a drive voltage to each of the light emitting elements via a power line,
While taking each of the light emitting elements individually in sequence, a current value flowing on the power supply line at a timing at the time of light emission of each of the light emitting elements is obtained as a measured current value, and is associated with each pixel and stored in the memory. Current measuring means for storing;
A luminance level indicated by pixel data of each pixel corresponding to the input image signal is corrected based on the measured current value stored in the memory in association with one of the pixels corresponding to the pixel data Brightness correction means for obtaining brightness correction pixel data, and light emission drive means for causing the light emitting element to emit light only during a period corresponding to the brightness correction pixel data in an image display light emission period in each frame period of the input image signal. Have.

[0009] A method of driving a display panel according to the present invention is a method of driving a display panel in which a plurality of light-emitting elements each carrying a pixel are arranged in a matrix. A current that obtains a measured current value corresponding to each pixel by taking in a current value flowing on a power supply line for supplying a drive voltage to each of the light emitting elements at a timing at the time of light emission of each of the light emitting elements while sequentially and independently emitting light. The measurement process and the luminance level indicated by the pixel data of each pixel corresponding to the input image signal are corrected based on the measured current value associated with one of the pixels corresponding to the pixel data. A brightness correction step of obtaining brightness correction pixel data, and the brightness correction pixel data during an image display emission period in each frame period of the input image signal. Having a light emission driving step for emitting only the light emitting element corresponding period.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 is a diagram showing a configuration of an electroluminescent display device (hereinafter, referred to as an EL display device) according to the present invention. As shown in FIG. 3, the EL display device includes a drive voltage generation circuit 1, a current detection circuit 2, a multiplier 3, a drive control circuit 4, a scan line driver 5, a data line driver 6, an operation device 7, a light emission drive current value. Memory 8, non-light emission current value register 9
A, a representative current value register 9B and a display panel 10.

The display panel 10 has an anode power supply line 1
6, the scanning lines A 1 to A n, and m data lines B 1 .about.B m arranged in intersecting each scanning line responsible for the n number of horizontal scanning lines each cathode power line 17,1 screen respectively Is formed. The drive voltage Vc is applied to the anode power supply line 16, and the cathode power supply line 17 is grounded. Further, EL units E 1,1 to En , m each serving as a pixel are formed at intersections of the scanning lines A 1 to An and the data lines B 1 to B m on the display panel 10.
Note that the internal configuration of the EL unit E is the same as that shown in FIG. 2 as described above, and a description thereof will be omitted.

The drive voltage generation circuit 1 generates the DC drive voltage Vc and applies it to the anode power supply line 16 of the display panel 10 via the current detection circuit 2. The current detection circuit 2 detects a current flowing on the anode power supply line 16,
A current value data signal CD indicating the detected current value is supplied to the drive control circuit 4. The current detection circuit 2 includes a drive voltage generation circuit 1 and a display panel 10 as shown in FIG.
, A resistor R1, a measurement switch SW, and an A / D converter AD connected between the anode power supply lines 16. The measurement switch SW is turned off while the drive control circuit 4 supplies the logic level 1 current detection enable signal CE, and turned on while the logic level 0 current detection enable signal CE is supplied. To short-circuit both ends of the resistor R1. That is, while the measurement switch SW is in the off state, the current detection circuit 2 is in a current detection operation state, and supplies a voltage generated across the resistor R1 to the A / D converter AD in accordance with the current value. At this time, A / D
The converter AD converts the voltage generated at both ends of the resistor R1 into a digital value and converts the value obtained by converting the voltage into a current value data signal CD.
To the drive control circuit 4.

The multiplier 3 is sequentially supplied with pixel data PD for each pixel based on an image signal carrying an image to be displayed on the display panel 10. At this time, the pixel data PD indicates a display luminance level for each pixel. The multiplier 3 receives the input pixel data PD for each pixel.
The luminance correction pixel data LD obtained by multiplying the luminance control pixel data LD by the luminance correction value K supplied from the drive control circuit 4 is supplied to the drive control circuit 4. That is, the drive control circuit 4 controls the display panel 10
Each time the pixel data PD corresponding to each of the EL units E 1,1 to En , m carrying the pixels of the above is sequentially input, the measured current value for each pixel, which has been measured in advance, is stored in the light emission drive current value memory. 8
And a luminance correction value K corresponding to the measured current value.
Is generated and supplied to the multiplier 3. The details of the operation of measuring the measured current value for each pixel and the operation of generating the luminance correction value K will be described later.

The operating device 7 receives various operations by the user and supplies various command signals corresponding to the operations to the drive control circuit 4. For example, the operation device 7 includes the display panel 1
A power-on signal ON is supplied to the drive control circuit 4 in response to a power-on operation performed by a user to start a display operation by 0. On the other hand, the operating device 7 supplies a power-off signal OFF to the drive control circuit 4 in response to a power-off operation performed by the user to stop the display operation. The operation device 7 supplies a luminance correction control signal LAD to the drive control circuit 4 in response to a luminance correction command operation by the user.

The drive control circuit 4 controls the power-on signal ON
In response to the above, while performing the operation of generating the luminance correction value K (to be described later), the display panel 10 is set to have a gray scale to realize the halftone luminance display based on the luminance correction pixel data LD on the display panel 10. Drive control. At this time, various gray scale methods are conceivable for gray scale driving of the display panel 10. Here, a case where the display panel 10 is implemented by a sub-frame method will be described as an example.

In the subframe method, a display period of one frame is divided into N subframes, and a different light emitting period is assigned to each subframe. Then, according to the luminance level indicated by the pixel data, by determining a combination of subframes for performing light emission,
The intermediate luminance is expressed at the (2 N +1) stage.
The drive control circuit 4 sends various drive control signals to drive the display panel 10 by the drive using the sub-frame method to the scan line driver 5 and the data line driver 6.
To supply.

The operation of the scanning line driver 5 and the data line driver 6 will be described below, taking as an example the case where the display panel 10 is driven by dividing the display period of one frame into three sub-frames SF1 to SF3 as shown in FIG. Will be described. Scan line driver 5, the subframe SF1~SF3 in each as shown in FIG. 5, sequential scan lines A 1 to A n each display panel 10, continue to apply an alternative scanning pulse. During this time, the data line driver 6 applies the pixel data pulses DP 1 to DP m corresponding to each of the m pieces of luminance correction pixel data LD corresponding to each of the m pixels existing on each scan line to the scan pulse application timing. In synchronization with the data lines B 1 to B m . It should be noted that the pixel data pulse DP is generated within the subframe by EL
The unit E has a pulse voltage of a high voltage when emitting light, and a low voltage (for example, 0 volt) when not emitting light. At this time, the EL unit E connected to the scan line A to which the scan pulse is applied becomes a target of writing pixel data.
The FET 11 in the EL unit E to which the pixel data is to be written is turned on in response to the scan pulse, and the pixel data pulse DP supplied via the data line B is supplied to the gate G of the FET 12 and the capacitor 13.
Respectively. The FET 12 generates a light emission drive current according to the pulse voltage of the pixel data pulse DP, and supplies this to the EL element 15. That is, the EL element 15
When the pixel data pulse DP of a high voltage is supplied, the light emission state is caused by the light emission drive current. On the other hand, when the low-voltage pixel data pulse DP is supplied, the pixel enters a non-light emitting state. At this time, the subframe S as shown in FIG.
When a high-voltage pixel data pulse DP is supplied to the EL element 15 in F1, the EL element 15 sets "1".
Light emission is continued for a certain period. When a high-voltage pixel data pulse DP is supplied to the EL element 15 in the sub-frame SF2, the EL element 15
Light emission is continued for a period of 2 ". When a high-voltage pixel data pulse DP is supplied to the EL element 15 in the sub-frame SF3, the EL element 15
Keeps emitting light for a period of "4".

Therefore, for example, the sub-frames SF1 to SF
When light emission is performed only in SF3 of No. 3, light emission is performed only in the period of "4" in one frame display period.
The luminance corresponding to the light emission period “4” is visually recognized by human eyes.
When light emission is performed in the sub-frames SF1 and SF3, “1” + “4” = “within one frame display period”.
Since the light emission is performed only during the period of 5 ", the human eye can see the luminance corresponding to the light emission period of" 5 ". Similarly, when the light emission is performed in the sub-frames SF2 and SF3, 1 is obtained.
Since light emission is performed only during the period of “2” + “4” = “6” in the frame display period, the luminance corresponding to the light emission period “6” is visually recognized by human eyes.

As described above, when the display panel 10 is driven by using the three sub-frames as shown in FIG. 5, it is possible to express an intermediate luminance of 9 gradations by the combination of the sub-frames that emit light. It becomes. On the other hand, the drive control circuit 4 executes a light emission drive current measurement routine as shown in FIG. 6 according to the power-off signal OFF.

In FIG. 6, first, the drive control circuit 4
A drive control signal for turning off the FETs 12 in all the EL units E 1,1 to En , m is supplied to each of the scan line driver 5 and the data line driver 6 (step S1). Next, the drive control circuit 4 supplies the current detection enable signal CE of the logic level 1 to the current detection circuit 2 (Step S2). As a result, the current detection circuit 2 detects the voltage generated across the resistor R1 in accordance with the current flowing on the anode power supply line 16, and sends a current value data signal CD having the detected voltage value to the drive control circuit 4. Supply. That is, when the operations of all the EL units E 1,1 to En , m are stopped, the current flowing on the anode power supply line 16 is detected. Next, the drive control circuit 4 stores the current value indicated by the current value data signal CD in the non-light-emission current value register 9A as a non-light-emission current value flowing during the non-display operation by the display panel 10 (step S).
3). Next, the drive control circuit 4 stores “1” as an initial row number in a row number register X (not shown) and “1” as an initial column number in a column number register Y (not shown). Is stored (step S4). Next, the drive control circuit 4
L units E 1, 1 to E n, of m, the line number register X to the stored line number and column number register Y EL unit corresponding to the column number stored in the E X, Y only emission A drive control signal to be driven is supplied to each of the scanning line driver 5 and the data line driver 6 (Step S5).
By the execution of step S5, the scan line driver 5, among the scanning lines A 1 to A n, a scan pulse is applied only to the scanning line A X indicated by the line number stored in the row number register X. At the same time, the data line driver 6 applies a high voltage only to the data line BY indicated by the column number stored in the column number register Y among the data lines B 1 to B m , and to the other data line B groups. Applies a low voltage pixel data pulse DP. By the above operation, the light emission drive current flows only to the EL element 15 formed in the EL unit EX , Y among the EL units E 1,1 to En , m , and the EL element 15 emits light. I do. Therefore, only the light emission drive current consumed by the EL units E X, EL elements 15 in the Y is flowing on the anode power supply line 16. At this time, the current detection circuit 2 outputs the current value data signal CD indicating the value of the current flowing on the anode power supply line 16.
Is supplied to the drive control circuit 4.

Here, the drive control circuit 4 takes in the current value indicated by the current value data signal CD and uses it as a measured current value in the address of the light emission drive current value memory 8.
[X, Y] is stored (step S6). Next, the drive control circuit 4 increments the column number stored in the column number register Y by 1 (step S7). Next, the drive control circuit 4 determines whether or not the column number stored in the column number register Y is larger than the last column number m.
(Step S8). If it is determined in step S8 that the column number stored in the column number register Y is not larger than the final column number m, the drive control circuit 4
Returning to the execution of step S5, the operation as described above is repeatedly executed.

For the repetition of steps S5 to S8,
According to the row number stored in the row number register X,
Scan line A shownXEL unit E on topX, 1
~ E X, mFlow into the EL elements 15 formed in each
The light emission drive current is measured sequentially and individually, and the light emission drive current value
It is stored in the memory 8. On the other hand, step S
8, the column number stored in the column number register Y
Is determined to be greater than the last column number m,
The operation control circuit 4 determines whether the row stored in the row number register X
The number is incremented by 1 and written to the column number register Y.
The stored column number is rewritten to 1 (step S9).
That is, by performing the step S9, the light emission drive is performed.
An EL unit group E to be measured is formed.
Scan line AXTo the next scan line AX + 1Migrate to
It is. Here, the drive control circuit 4 operates in a row number register
If the line number stored in X is larger than the last line number n,
It is determined whether or not there is (step S10). Such a stage
In step S10, the data stored in the row number register X is stored.
Line number is not greater than the last line number n
In this case, the drive control circuit 4 executes the above-described step S5.
Return The operation as described above is repeatedly executed.

According to the repetition of steps S5 to S10, all the ELs formed on the display panel 10 are
Unit E1, 1 to E n, individually emission drive current to the EL element 15 in the m each is measured, than is stored in the light emission drive current value memory 8 of the measurement results is associated with each pixel . If it is determined in step S10 that the row number stored in the row number register X is larger than the last row number n, the drive control circuit 4 stores the data in the light emission drive current value memory 8. The smallest current value is searched for among the measured current values for each pixel, and the current value is stored in the representative current value register 9B as a representative current value (step S11). Next, the drive control circuit 4 sets the logic level to 0.
Is supplied to the current detection circuit 2 (step S12). As a result, both ends of the resistor R1 provided in the current detection circuit 2 are short-circuited, so that the drive voltage Vc generated by the drive voltage generation circuit 1 is directly applied to the anode power supply line 16. Step S above
After the execution of step 12, the drive control circuit 4 exits the light emission drive current measurement routine and returns to the execution of the main routine (not shown).

At this time, the light emission drive current measurement routine is executed in response to a power-off operation performed by the user to stop the display operation on the display panel 10 as described above. That is, during the period when the display operation based on the image data is not performed, the EL of each pixel
The light emission drive current flowing when the element 15 emits light alone is measured, and the measurement result is stored in the light emission drive current value memory 8 as a measured current value.

Here, when the user performs a power-on operation using the operation device 7 in order to start a display operation by the display panel 10, the operation device 7 supplies a power-on signal ON to the drive control circuit 4. In response to the power-on signal ON, the drive control circuit 4 executes a brightness correction value generation routine as shown in FIG. 7 to generate the brightness correction value K corresponding to the input pixel data PD.

In FIG. 7, first, the drive control circuit 4
The determination as to whether or not the pixel data PD has been input is repeatedly performed until the input of the pixel data PD is performed (step S21). If it is determined in step S21 that the pixel data PD has been input, the drive control circuit 4
Reads the measured current value corresponding to the pixel corresponding to the input pixel data PD from the light emission drive current value memory 8
(Step S22). Next, the drive control circuit 4 obtains a division result obtained by dividing the representative current value stored in the representative current value register 9B by the measured current value as a luminance correction value K.
(Step S23), this is supplied to the multiplier 3 (Step S24). Therefore, the multiplier 3 generates luminance correction pixel data LD having a value represented by the following equation for each pixel.

LD = pixel data PD / brightness correction value K = pixel data PD · (representative current value / measured current value) Next, the drive control circuit 4 determines whether or not the power-off signal OFF is supplied from the operation device 7 (Step S2
5). In step S25, the power-off signal OF
When it is determined that F is not supplied, the drive control circuit 4 returns to the execution of step S21 and repeatedly executes the above-described operation. On the other hand, if it is determined in step S25 that the power-off signal OFF has been supplied,
The drive control circuit 4 exits the brightness correction value generation routine and proceeds to the execution of a light emission drive current measurement routine as shown in FIG.

According to the execution of the luminance correction value generation routine, as the light emission drive current measured for each pixel becomes larger than the representative current value, the EL element 15 in the EL unit E corresponding to the pixel is activated. A luminance correction value K for which the period during which light is to be emitted should be shorter than the period indicated by the pixel data PD.
Is generated. Then, a value obtained by multiplying the pixel data PD supplied corresponding to the pixel by the luminance correction value K is obtained as the luminance correction pixel data LD.

For example, when the measured current value of the EL element 15 formed in the EL unit E 1,1 is 12
In the case of 0%, the luminance correction value K is 0.83, and the value obtained by multiplying the pixel data PD supplied corresponding to the EL unit E 1,1 by 0.83 is the luminance correction pixel data L.
D. The measured current value of the EL element 15 formed in the EL units E 1 , 2 is 110% of the reference voltage value.
, The luminance correction value K becomes 0.91, and this E
Pixel data PD supplied corresponding to the L units E 1,2
Is multiplied by 0.91 to obtain the luminance correction pixel data LD.

That is, the EL element 15 having a small emission drive current is compared with the EL element 15 having a large emission drive current.
The luminance correction is performed on the pixel data PD so that the light emission period in each frame is shorter than that of the pixel data PD. That is, the EL element 15 having a large light emission drive current has a higher luminance during light emission than the EL element 15 having a small light emission drive current, but corresponds to the EL element 15 having a large light emission drive current. The apparent luminance on the screen is made uniform by shortening the light emission period per frame by the pixel data PD.

Therefore, even if the emission luminance of each EL element corresponding to each pixel varies due to driving the display panel 10 for a long time, it is possible to provide a high quality image display without luminance unevenness. It becomes. In the above embodiment, the smallest current value among the measured current values for each pixel stored in the light emission drive current value memory 8 is set as the representative current value, but the largest current value is set as the representative current value. It may be a value. At this time, the drive control circuit 4 searches for the largest current value among the measured current values for each pixel stored in the light emission drive current value memory 8 in step S11 shown in FIG. The current value is stored in the representative current value register 9B as a representative current value. As a result, with reference to the EL element 15 having the largest light emission drive current, the luminance of the pixel data PD is corrected so that the EL element 15 having the smallest light emission drive current has a longer light emission period in one frame. You. At this time, the brightness correction value K is always larger than 1.
Therefore, when obtaining the luminance correction pixel data LD by multiplying the input pixel data PD by the luminance correction value K, multiplication by a predetermined coefficient (less than 1) is further performed. For example, assuming that the predetermined coefficient is 0.7, LD = pixel data PD · 0.7 · luminance correction value K = pixel data PD · 0.7 (representative current value / measured current value). can get.

In the above embodiment, the value of the light emission drive current actually measured for each pixel is stored in the light emission drive current value memory 8 as a measured current value. The difference from the representative current value may be stored in the light emission drive current value memory 8 in association with each pixel. In addition, there may be a small amount of current consumed inside the display panel 10 in addition to the light emission drive current flowing into the EL element 15 itself. Therefore, in order to accurately measure the light emission drive current flowing into the EL element 15 itself, the current detection circuit 2
A value obtained by subtracting the non-light-emitting current value stored in the non-light-emitting current value register 9A from the current value detected by the above-described method may be stored in the light-emitting drive current value memory 8 as a final measured current value.

If the measured current value obtained by individually measuring the light emission drive current flowing for each pixel is out of the specified current value range, the drive control circuit 4 determines the measured current value. It is determined that the EL unit E carrying the pixel corresponding to the pixel has failed, and the luminance correction value K corresponding to the pixel is "0".
May be supplied to the multiplier 3. At this time, since the pixel data PD is multiplied by 0, the luminance correction pixel data LD becomes 0, and the EL element 15 corresponding to the pixel is always turned off. That is, the drive control circuit 4
Inhibits the light emitting operation for the EL unit E corresponding to the failed pixel.

Further, in the above embodiment, the light emission drive current measurement routine as shown in FIG. 6 is executed only once in response to the power-off operation by the user, but this is repeatedly executed periodically. You may do it. Further, the timing for starting the execution of the light emission drive current measurement routine is not limited to the power-off operation by the user. For example, when the EL display device itself shown in FIG. 3 is mounted as a display device of various portable information terminal devices such as a mobile phone, the charging operation of the portable information terminal device or the display on the display panel 10 is performed. The light emission drive current measurement routine may be executed when the surface is closed. Further, it may be forcibly executed in response to a luminance correction command operation by a user. On this occasion,
When the operating device 7 supplies the brightness correction control signal LAD to the drive control circuit 4 in response to the brightness correction command device, the drive control circuit 4 executes the light emission drive current measurement routine shown in FIG. Is performed. As shown in FIG. 8, in each frame, a light emission drive current measurement period HT is provided in addition to the sub-frames SF1 to SF3 as described above.
The above-mentioned light emission drive current measurement routine may be executed within the routine. That is, the light emission drive current of each pixel is measured by executing the light emission drive current measurement routine in a period other than the image display light emission period including the sub-frames SF1 to SF3 in each frame.

In the above embodiment, the light emission drive current
Current detection circuit 2 for actually detecting the
And between the anode power supply line 16,
Driving voltage generating circuit 1 includes a plurality of independent driving voltage generating circuits
In the case of the configuration with
A flow detection circuit may be provided. For example, in FIG.
In this case, the driving voltage generating circuit 1
Pressure generation circuit 1R, green light emission drive voltage generation circuit 1G, and
Blue light emission drive voltage generation circuits 1B are provided independently of each other.
ing. The red light emission drive voltage generation circuit 1R is connected to a display panel
EL unit E formed in 101,1~ En, mWithin
Anode power line for each of the EL units E responsible for red emission
A driving voltage is supplied via 16R. Green light emission drive
The voltage generation circuit 1G is formed on the display panel 10.
EL unit E1, 1~ En,mEL light emitting green light
Drive power is supplied to each of the knits E via the anode power supply line 16G.
Supply pressure. The blue light emission drive voltage generation circuit 1B
EL unit E formed on display panel 101,1~
En, mEach of the EL units E responsible for emitting blue light within
A drive voltage is supplied via the pole power line 16B. this
At this time, the red light emission drive voltage generation circuit 1R and the anode power supply line
During 16R, the current detection circuit 2R generates the green light emission drive voltage.
Current detection circuit 2 between path 1G and anode power line 16G
G, blue light emission drive voltage generation circuit 1B and anode power supply line
The current detection circuits 2B are provided between the 16Bs respectively, and the current
It does the detection.

In FIG. 10, as the drive voltage generating circuit 1, a first area display drive voltage generator 1a and a second area display drive voltage generator 1b are provided independently. First region display drive voltage generating circuit 1a
Supplies a drive voltage via the anode power supply line 16a to each of the EL units E responsible for image display in the first screen area GM1 in the screen of the display panel 10. The second region display drive voltage generation circuit 1b is a second region display drive voltage generation circuit 1b.
A drive voltage is supplied via the anode power supply line 16b to each of the EL units E responsible for displaying images in the screen area GM2. At this time, the current detection circuit 2a, the second region display drive voltage generation circuit 1b, and the anode power supply line 16b are provided between the first region display drive voltage generation circuit 1a and the anode power supply line 16a.
The current detection circuits 2b are provided between them, and the currents are individually detected. In FIG. 10, one panel is divided into two regions. However, the number of regions is not limited to two. Of course, the division is performed based on both the scale of the current detection circuit and the detection speed. The number can be set arbitrarily.

[0037]

As described above, according to the present invention, the light emission drive current value flowing when each light emitting element which carries out each pixel emits light individually is measured in association with each pixel, and the input current is measured. Based on the light emission drive current value associated with the pixel corresponding to the pixel data, the luminance of the input pixel data is corrected.

Therefore, according to the present invention, even if the emission luminance of each light emitting element serving as each pixel varies due to driving the display panel for a long time, a high quality image display without luminance unevenness is provided. can do.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an active matrix drive type EL display device.

FIG. 2 is a diagram illustrating an example of an internal configuration of an EL unit E that carries each pixel.

FIG. 3 shows an active matrix drive type E according to the present invention.
It is a figure showing composition of an L display device.

FIG. 4 is a diagram illustrating an example of an internal configuration of a current detection circuit 2.

FIG. 5 shows a display period of one frame divided into three sub-frames S;
FIG. 9 is a diagram illustrating an example of a light emission drive format in the case of driving divided into F1 to SF3.

FIG. 6 is a diagram showing a light emission drive current measurement routine executed by the drive control circuit 4.

FIG. 7 is a diagram showing a luminance correction value generation routine executed by the drive control circuit 4.

FIG. 8 is a diagram illustrating a light emission drive format in one frame display period when a light emission drive current measurement period HT is provided.

FIG. 9 is a diagram showing an example of installation of a current detection circuit 2 when a drive voltage generation circuit is provided exclusively for each color.

FIG. 10 is a diagram showing an installation example of a current detection circuit 2 when a drive voltage generation circuit is provided exclusively for each screen area of the display panel 10.

[Description of Signs of Main Parts]

1 Drive voltage generation circuit 2 Current detection circuit 3 Multiplier 4 Drive control circuit 8 Light emission drive current value memory 10 Display panel

Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat II (Reference) G09G 3/20 G09G 3/20 642P H05B 33/14 H05B 33/14 A (72) Inventor Hideo Ochi Fujimi, Tsurugashima-shi, Saitama 6-1-1, Pioneer Corporation Research Laboratory (72) Inventor Tsuyoshi Sakamoto 6-1-1, Fujimi, Tsurugashima-shi, Saitama F-term in Pioneer Corporation General Research Laboratory 3K007 AB17 BA06 DB03 GA04 5C080 AA06 BB05 DD05 EE28 FF11 GG12 HH11 JJ02 JJ03 JJ07

Claims (20)

[Claims]
1. A display panel driving device for driving a display panel in which a plurality of light emitting elements for each pixel are arranged in a matrix, wherein a driving voltage is applied to each of the plurality of light emitting elements via a power supply line. A drive voltage generating circuit to be supplied, and a current value flowing on the power supply line taken at the timing of light emission of each of the light emitting elements is obtained as a measured current value while causing each of the light emitting elements to emit light individually in sequence. A current measuring means for storing in a memory in association with a pixel; and a luminance level indicated by pixel data for each pixel corresponding to an input image signal, associated with one of the pixels corresponding to the pixel data. A brightness correction unit that obtains brightness correction pixel data by performing correction based on the measured current value stored in the memory; and within each frame period in the input image signal, A light emission drive unit for causing the light emitting element to emit light only during a period corresponding to the luminance correction pixel data in an image display light emission period in the display panel drive device.
2. The method according to claim 1, wherein the current measuring means controls a current value flowing through the power supply line at a timing when each of the light emitting elements emits light, while causing each of the light emitting elements to emit light independently in sequence outside the image display light emitting period. 2. The display panel driving device according to claim 1, further comprising means for storing the acquired data as the measured current value in a memory in association with each of the pixels.
3. The current measuring means captures a current value flowing on the power supply line at a timing when each of the light emitting elements emits light, in accordance with a luminance correction command, while sequentially causing each of the light emitting elements to emit light independently. 2. The display panel driving device according to claim 1, further comprising means for storing the measured value in the memory as the measured current value in association with each of the pixels.
4. The current measuring means includes: a scanning light emission driving means for sequentially and independently emitting light from each of the light emitting elements; a current detection circuit for detecting a current value flowing on the power supply line; Means for taking in the measured current value at the timing of light emission of each of the light emitting elements and storing the measured current value in the memory as the measured current value in association with each of the pixels. The driving device of the display panel according to the above.
5. A current detection circuit comprising: a resistor connected in series to the power supply line; means for extracting a voltage value generated at both ends of the resistor as the current value; A switch that shorts both ends,
The driving device for a display panel according to claim 4, comprising:
6. The non-light-emitting current measurement means for obtaining a value of a current flowing on the power supply line as a non-light-emitting current value when all the light-emitting elements formed on the display panel are turned off. Means, and a light-emitting current measuring means for obtaining, as a light-emitting drive current value, a current value taken at the time of light-emitting of each of the light-emitting elements while a current value flowing on the power supply line while causing each of the light-emitting elements to independently emit light sequentially 2. The display panel driving device according to claim 1, further comprising: means for storing a subtraction result obtained by subtracting the non-light emission current value from the light emission drive current value in the memory as the measurement current value.
7. A brightness correction value calculating means for obtaining a brightness correction value from the measured current value associated with one of the pixels corresponding to the pixel data, the brightness correction means comprising: A multiplier for obtaining a multiplication result obtained by multiplying the brightness correction value as the brightness correction pixel data,
The driving device for a display panel according to claim 1, further comprising:
8. The display panel driving device according to claim 7, wherein said brightness correction value calculating means obtains said brightness correction value that decreases as said measured current value increases.
9. The display panel driving device according to claim 7, wherein said brightness correction value calculation means obtains said brightness correction value which increases as said measured current value decreases.
10. A means for detecting, as a defective pixel, a pixel corresponding to a measured current value out of a predetermined current value range in each of the measured current values stored in the memory. 2. The display panel driving device according to claim 1, further comprising means for prohibiting a light emitting operation for the light emitting element corresponding to the failed pixel.
11. The first driving circuit for supplying a driving voltage via a first power supply line to each of the light emitting elements that emit red light among the light emitting elements formed on the display panel. A voltage generating circuit, a second driving voltage generating circuit for supplying a driving voltage via a second power supply line to each of the light emitting elements that emit blue light among the light emitting elements formed on the display panel, and the display. A third power supply voltage is supplied to each of the light emitting elements that emit green light among the light emitting elements formed on the panel through a third power supply line.
A drive voltage generation circuit, wherein the current detection circuit detects a current flowing on the first power supply line, and a second current detection detects a current flowing on the second power supply line 5. The display panel driving device according to claim 4, comprising: a circuit; and a third current detection circuit for detecting a current flowing on the third power supply line.
12. The driving voltage generating circuit, via a first power supply line, to each of the light-emitting elements for displaying an image in a first screen area of a screen when the display panel is divided into a plurality of areas. A first driving voltage generating circuit for supplying a driving voltage to each of the light emitting elements for driving an image display in a second screen area different from the first screen area in the screen via a second power supply line A second drive voltage generation circuit for supplying a voltage, wherein the current detection circuit detects at least a current flowing on the first power supply line;
5. The display panel driving device according to claim 4, further comprising a second current detection circuit for detecting a current flowing on the power supply line.
13. A display panel driving method for driving a display panel in which a plurality of light-emitting elements each carrying a pixel are arranged in a matrix, wherein each of said light-emitting elements emits light individually sequentially. A current measuring step of obtaining a measured current value corresponding to each pixel by capturing a current value flowing on a power supply line for supplying a drive voltage to each of the light emitting elements at a timing of light emission of each of the light emitting elements; A luminance correction step of correcting a luminance level indicated by pixel data for each pixel based on the measured current value associated with one of the pixels corresponding to the pixel data to obtain luminance corrected pixel data; The light emitting element emits light only during a period corresponding to the luminance correction pixel data in an image display light emitting period in each frame period of the input image signal. The driving method of a display panel and having a light emitting drive step for.
14. The method according to claim 1, wherein the current measuring step includes controlling the current flowing on the power supply line to emit light from each of the light emitting elements at the timing of light emission of each of the light emitting elements while the light emitting elements emit light independently in sequence outside the image display light emitting period. 14. The method of driving a display panel according to claim 13, further comprising a step of obtaining a measured current value corresponding to each pixel by taking in.
15. The current measuring step according to a brightness correction command, sequentially taking each of the light emitting elements individually and taking in a current value flowing on the power supply line at a timing when each of the light emitting elements emits light. 14. The method according to claim 13, further comprising the step of obtaining a measured current value corresponding to each pixel.
16. The non-light-emission current measurement step of obtaining a current value flowing on the power supply line as a non-light-emission current value when all the light-emitting elements formed on the display panel are turned off. A light emission current measurement step of obtaining a current value taken at the timing of light emission of each of the light emitting elements as a light emission drive current value while causing each of the light emitting elements to emit light independently in sequence. 14. The method of driving a display panel according to claim 13, comprising: a step of setting a result of subtracting the non-emission current value from the emission drive current value to the measured current value.
17. A brightness correction value calculating step for obtaining a brightness correction value from the measured current value associated with one of the pixels corresponding to the pixel data, the brightness correction step comprising: 14. The display panel driving method according to claim 13, further comprising: a multiplication step of obtaining a multiplication result obtained by multiplying the luminance correction value as the luminance correction pixel data.
18. The display panel driving method according to claim 17, wherein said luminance correction value calculation step obtains said luminance correction value that decreases as said measured current value increases.
19. The display panel driving method according to claim 17, wherein said brightness correction value calculation step obtains said brightness correction value which increases as said measured current value decreases.
20. Means for detecting, as a defective pixel, a pixel corresponding to a measured current value out of a predetermined current value range in each of the measured current values, wherein the light emission driving means includes a light emitting unit corresponding to the failed pixel. 14. The method of driving a display panel according to claim 13, further comprising means for inhibiting a light emitting operation of the element.
JP2001401814A 2001-12-28 2001-12-28 Device and method for driving display panel Pending JP2003202836A (en)

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JP2001401814A JP2003202836A (en) 2001-12-28 2001-12-28 Device and method for driving display panel
US10/322,776 US7274363B2 (en) 2001-12-28 2002-12-19 Panel display driving device and driving method
AU2002356439A AU2002356439A1 (en) 2001-12-28 2002-12-20 Panel display driving device and driving method
CN 02828406 CN1703731B (en) 2001-12-28 2002-12-20 Panel display driving device and driving method
EP02806068.9A EP1459285B1 (en) 2001-12-28 2002-12-20 Panel display driving device and driving method
PCT/JP2002/013374 WO2003058594A1 (en) 2001-12-28 2002-12-20 Panel display driving device and driving method
TW91137196A TW575859B (en) 2001-12-28 2002-12-24 Panel display driving device and driving method

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